1. Field of the Invention
The present invention relates to data processing systems and in particular to a graphical user interface for interacting with application or operating system software.
2. Description of the Related Art
In data processing systems a list of available machine or program functions or variables which may be selected by the operator is often shown on the display screen in the form of a menu. In some systems the title or a representation of each function or variable is displayed beside a corresponding letter or numeral. The desired function or task may be selected from the menu by typing the alphanumerical character on the command line. In other systems the desired function may be selected by positioning the cursor or mouse pointer under the title or other representation of the desired function. In some menu displays the first item in the menu is highlighted. The highlighting can be repositioned on another item in the menu by using the cursor movement keys. The desired choice of item is selected by pressing the "enter" key when that item is highlighted. Very often in menu user interfaces the choice of one item from the menu causes another menu to be displayed on the screen showing what further choices are available as result of the previous choice. As a result of making this further choice yet another menu may be displayed on the screen.
A known way of simplifying such a hierarchical menu system in which one menu choice leads to another menu of choices is to display the first menu as a menu bar at the top of the display screen. Each of the choices in the menu bar can be "pulled down" to display the next menu in the hierarchy, usually in the form of a display window.
These types of user interfaces are satisfactory when the number of choices is small. However as more complex options are presented to the user, the hierarchy of menus can quickly increase to the point where navigation through the menu system becomes difficult. For example, after an operator has descended to say the third level of a menu hierarchy, i.e. the third menu in the series to be displayed on the screen, he may have forgotten the alternatives he chose from at the top level, or have even lost track of where he is in the overall choice structure. In either case the operator has to "back up" the hierarchy to check on his position.
An alternative has been to use a "cascaded menu" as is supported in the IBM 0S/2 Presentation Manager (trademarks of IBM Corp.) Release 1.2 operating system. A menu is displayed in a display window and when a choice is made from this menu the menu from the next level is displayed in a window adjacent to the window from which the first choice was made. This arrangement certainly helps navigation through a complex window hierarchy but only shows a limited subset of the structure in which the operator is navigating.